Migration from Joomla 1.5 to 2.5

I have migrated our website from Joomla 1.5 to 2.5
The eWay payment gateway plugin (v1.0) is visible in the backend but the Parameters panel shows "No Parameters"
The eWay gateway is not visible in the front-end.
I have tried to install the latest version of the eWay plugin but get the message

A plugin with the name: os_eway existed already

I tried to uninstall the plugin but it remains in the list.

I'm stuck and would really appreciate some advise on how to proceed.

Hi John

Please submit a support ticket sending us administrator and FTP account of your site so that I can check and solve it for you.

Tuan